Wiring into an external garage one meter from house?

[holmslaw]

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[Adam_151]

This is getting stupid....

Can we just all accept that the arrangement which was suggested earlier is compliant with BS7671 but is rather poor, rather like the green/yellow core sleeved as live is, and move on?.... please!

 

[JohnW2]

This is getting stupid.... Can we just all accept that the arrangement which was suggested earlier is compliant with BS7671 but is rather poor, rather like the green/yellow core sleeved as live is, and move on?.... please!

Yes, very stupid - I'll second that.

As a contradiction -)), I would just add (as a 'final' comment!) that a major concern over the 32A MCB/2.5mm² cable/one socket design is that, even if arguably BS7671-complaint, someone, maybe a DIYer, could come across this circuit subsequently and 'innocently' add sockets (without seemingly needing notification), without realising that the CCC of the cable could thereby be exceeded. Coupled with the fact that there's no conceivable advantage in having a 32A OPD (rather than 16A or 20A), and I think that adds up to very good reasons for not doing it!

Kind Regards, John.

 

[ricicle]

It's an excellent analogy.

Why can't you answer my simple question? The ridiculous circuit you describe would comply with 433.3, but only in very specific situations, none of which exist in the average house.

It's not a ridiculous circuit at all. Have you never wired a spur off a ring final circuit in a domestic house then ? What would be the protective device for that single 2.5mm² t+e - that would be 30/32A ? or have you forgotten that you rely on the loading never being greater than 26 A for O/L protection that is why it is permitted

Sorry for anyone who is bored but such a simple error by Holmslaw must be corrected.

 

[holmslaw]

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[Paul_C]

1) We are discussing things ONLY in the context of Schedule 4.

Never disputed. Or schedule 4 in conjunction with whatever other parts of the building regulations of which it is a part may have an effect.

2)

The cable can't be separated from the "work which consists of adding a socket," since it's a necessary part of that work.

Well, obviously as I said that I don't disagree with that either.

But I'm not going to bother to argue the point any more on Michael's thread.

I would just add (as a 'final' comment!) that a major concern over the 32A MCB/2.5mm² cable/one socket design is that, even if arguably BS7671-complaint, someone, maybe a DIYer, could come across this circuit subsequently and 'innocently' add sockets (without seemingly needing notification), without realising that the CCC of the cable could thereby be exceeded.

Which is already something to be considered with a 2.5 sq. mm unfused spur from a ring. But even if the regs. permit it, when we're talking about a dedicated 2.5 sq. mm circuit run from the panel to, say, a single socket of FCU where the fuse will provide protection, what's the point in fusing it at 32A at the origin anyway? You might just as well bring it down to 20A to give the cable a little extra protection.

As far as Michael's various proposals are concerned, if the project developed into running a new circuit from the board anyway, then for the amount of work involved one might just as well go up to a suitably sized cable and provide a 32A feed to the garage to allow for future expansion.

 

[holmslaw]

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[Paul_C]

And the assumed max current is 20A not 26A, where did you dream that up?

That's a flaw in the regs. They might assume that the maximum current on the spur will be 20A, but we all know that there's nothing to stop somebody plugging two 13A loads into a double socket.

 

[JohnW2]

If your very incorect interpretation of 433.3 was correct we could do away with most protective devices.

There would obviously always be a need for devices to provide fault protection, but you're probably right to question whether, in practice, overload protection actually achieves anything much, except in cases in which an installation is seriously abused.

The chances of any normal domestic circuit being overloaded to a large enough extent, and for a long enough time, for an OPD (rated per the cable's CCC) to operate is probably very small - so (rather contrary to 'intuition') II somewhat doubt that one would actually see a significant number of 'safety incidents' even if all circuits (including lighting) were protected by, say 40A or 45A MCBs.

Kind Regards, John.

 

[ricicle]

Ok, so you haven't a clue what 433.3 means, the circuit it describes is ok in areas with no "fire risk", hence my analogy with the matches.

There is a specific reg applicable to rfc's (can't be bothered to look it up) that allows a 2.5mm unfused spur. And the assumed max current is 20A not 26A, where did you dream that up?

That does not mean you can by design install cables with lower ratings than the protective device in any situation.

If your very incorect interpretation of 433.3 was correct we could do away with most protective devices. And if you can't understand that, there is something seriously lacking in your ability to apply and interconnect the regs.

It is you that has the problem. The 20A reg. is to do with the fact that the cables are allowed to be wired in the form of a ring in the first place - nothing to do with spurs. 26A is not dreamt up - it is quite a legimate assumption of what the possible maximum demand on a double socket could be...